Computer does not recognize my board - please help

hello please help me, i connect the rx with tx and reset with gnd. i connect the arduino with usb. the first time the device manager find the arduino,but i dont upload the programm and now the device manager not find the arduino.please help me

reset with gnd

Why ??????

Step #3 in the loop-back test.

@sotisanis: Are you saying that with nothing connected to the Arduino except a USB cable the computer does not recognize the Arduino?

Seems I was reading the post in a different way.

Connecting reset to GND and complaining about upload not working...

my computer unkown the cable of arduino. but before 2-3 days computer know the cable and arduino work ok. but yesterday and today nothing!!!PLEASE HELP ME!!!
i use arduino mega 2560 and windows vista. i use two diferrent computers and nothing

What did you do with it?

The loopback test apparently didn't work with drivers installed. The board seems to have worked a couple of days ago, so something must have happened to it.

As I see it, there are a couple of options:

a) try to get the little chip that does USB into 'DFU-mode' and re-upload the firmware b) find someone with a known-good AVR programmer in your town to check the chips c) buy an AVR programmer and do it yourself (about 20$) d) current board --> trash + buy a new one

a) to c) may or may not work. All of the above costs time and or money.